In the preparation of false teeth or caps, the dentist will normally prepare a negative impression of the affected tooth or teeth. The negative impression is normally obtained by filling a tray with polymer material and having the patient sink his teeth into the polymer material to create a plurality of depressions or cavities in the polymer material. After the polymer material cures, it is removed from the patient's mouth and hardens to from a semi-permanent impression of the patient's teeth and gum.
The negative impression of the patient's teeth and gums is used as a mold for developing a model of the patient's teeth to facilitate the production of a replacement tooth or other prosthetic. To form a tooth model, the quantity of casting stone, often referred to as die stone, is poured into the negative impression.
In the prior art, the base for the dental mold is made by one of two methods. First, additional hardenable stone, or plaster, is poured within the negative impression to cover the die stone and the retainer with sufficient depth of plaster to form a solid base. After both the die stone and the plaster have hardened, the tray and supported impression material is peeled away to leave a conventional dental model. Alternatively, a patty of yellow stone is formed upon a glass or other smooth surface. The completely cured die stone, with pins in place, is placed thereupon.
In either method, pins are lodged or fixated in the die stone to extend into and slidably engage the plaster. The pins serve the function of maintaining registration of the model tooth with the remaining model when the model tooth is replaced into the model base after a fabrication step.
All of the prior art methods for using dowel pins to produce a working model of the patient's teeth require that the model be removed from the mold at some step of the modeling process. This results in additional technician time and, therefore, adds to the cost of the dental model. In addition, the removal of the model from the mold tends to cause difficulties in obtaining precise alignment of the opposing sides of the model. In view of the foregoing difficulties, there is a need for a dental articulator and mold apparatus which allows a technician to produce a model of a patient's teeth without having to remove the model from the mold. This need is answered by the method and apparatus of the present invention, discussed in greater detail below.